GNU bug report logs - #56199
hash table equality predicate [PATCH]

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From: Mattias Engdegård <mattiase <at> acm.org>
To: 56199 <at> debbugs.gnu.org
Subject: bug#56199: hash table equality predicate [PATCH]
Date: Fri, 24 Jun 2022 19:19:54 +0200

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Recently[1] a predicate for structural equality was requested that also recurses through hash tables.
It showed that Emacs doesn't even come with a way of comparing hash tables. Third-party implementations exist but if the code quoted in [2] is representative, perhaps it would make sense to add a `hash-table-equal-p` predicate?
Even implemented entirely in Lisp it would be an order of magnitude faster (and actually correct).

The attached code is not without flaws but provides a rough starting point.
(This is not meant as a strong argument for or against adding it in the first place.)

[hash-table-equal-p.diff (application/octet-stream, attachment)]

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[1] https://lists.gnu.org/archive/html/emacs-devel/2022-06/msg00444.html
[2] https://lists.gnu.org/archive/html/emacs-devel/2022-06/msg00553.html

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